When a process is running on a computer system, the process uses designated portions of memory to store and retrieve data. Other processes may also have access to those designated portions of memory.
When a first process running on a computer system is stopped and later resumed, a second process running on the computer system while the first process was stopped may have access to the portion of memory previously used by the first process. If, while the first process is stopped, the second process overwrites data values which have been stored in the memory by the first process, then when the first process resumes, the data values which it had stored in memory before it had been stopped may no longer be available. This may create errors.
In addition, if several processes are running simultaneously in a computer system, one process may store data in a portion of memory being used by another process. Thus, prior to a process retrieving the data it had stored, that data may be corrupted.
It is also typical that a computer system may be subjected to a system restart. Such a computer system may have a software application running which provides data buffers whose contents are not erased as part of a system restart. This may be found, for example, in a software package known as Transaction Processing Facility (TPF) which is a product of IBM Corporation, Armonk, N.Y. In TPF, if there is a system restart, the contents of certain data buffers are not erased. After the restart is complete, when TPF continues running at the point it was at prior to the system restart, it is desirable that the contents of the non-erased data buffers remain the same. However, these data buffers are accessible to any application running on the system. These data buffers could therefore be corrupted by errors in either the operating system or the applications running on the operating system.